After you have integrated the baseband modem with the RF section to complete the radio, you need to test it again to verify overall performance. The capture and playback system can connect with an E4438C ESG or E8267D PSG to up-convert the digital IQ signals directly to RF or MW frequencies. Since these are the same signals that you used in baseband verification, you can easily compare the results and pinpoint the trouble spots. You can also use the RF signals to test the performance of your entire RF section or a component such as ADC or power amplifier.
Figure 3. By connecting
to an ESG or PSG vector signal generator, the N5110B can play back the
same custom IQ waveform file to generate analog IQ and RF signals.